A single amino acid mutation of contributes to resistant starch accumulation in rice.

Foods rich in resistant starch can help prevent various diseases, including diabetes, colon cancers, diarrhea, and chronic renal and hepatic diseases. Variations in starch biosynthesis enzymes could contribute to the high content of resistant starch in some cultivars of rice ( L.). Our previously published work indicated that the gene in the rice mutant line, 'Jiangtangdao1' was a putative allele of the rice starch branching enzyme gene (previously known as ); might control the biosynthesis of the high resistant starch content in the rice line. Biomolecular analysis showed that the activity of SBEs was significantly lower in soluble extracts of immature seeds harvested from 'Jiangtangdao1' 15 days after flowering than in the extracts of the wild-type rice line 'Huaqingdao'. We performed gene complementation assays by introducing the wild-type into the mutant 'Jiangtangdao1'. The genetically complemented lines demonstrated restored seed-related traits. The structures of endosperm amylopectin and the morphological and physicochemical properties of the starch granules in the transformants recovered to wild-type levels. This study provides evidence that is a novel allele of , responsible for biosynthesis of high resistant starch in 'Jiangtangdao1'.